1. Field of the Invention
The invention relates to a radio communication terminal and a radio communication system for transmitting and receiving a packet through an adhoc multihop communication network.
2. Description of the Related Arts
Adhoc multihop communication in which by sequentially transferring packets among nodes existing in a communication range, the packets can be also transmitted to nodes out of the communication range has been known. In the adhoc multihop communication, a multihop route is constructed and managed (what is called a routing process) by a system such as DSR (Dynamic Source Routing), OLSR (Optimized Link State Routing), or AODV (Adhoc On-Demand Distance Vector).
In the case where the malicious third party provided a bypass route as what is called a wormhole for the multihop route, there is such a problem that when the node has executed the routing process, the node erroneously sets the multihop route and continues the communication without being aware of the erroneous setting. Specifically speaking, dummy terminals are set at both ends of the multihop route, the dummy terminal set at one of the ends obtains a packet and falsifies data included in the packet, and thereafter, transmits the packet obtained after the falsification to the dummy terminal set at the other end by using a high-speed communication network such as optical fiber communication network or WiMAX as a bypass route. Each of the nodes which exchange the packets, therefore, exchanges the packet including the falsified data.
If the wormhole is, for example, a simple radio wave propagating route formed by reflecting a radio wave by accident from a large-sized truck which had stopped, since it is advantageous to communicate through the wormhole, the wormhole should be actively used. If the malicious third party purposely set the wormhole as mentioned above, there occurs such an obstacle that the packet including the falsified application data is received, or when only the application data included in the packet has selectively been abandoned, in spite of a fact that the multihop route has been established, the application data cannot be received.
For example, in the following Non-Patent Literature 1, a method of restricting an arrival range of the packet on a physical space by a geographical packet leash or a temporal packet leash has been disclosed. In the following Non-Patent Literature 2, there has been disclosed a method whereby only the node existing in a predetermined range sets a common key called a local broadcast key, so that even if a wormhole is formed between the node and the node existing out of the predetermined range, an encrypting process is made to fail by a difference of the common key.
Non-Patent Literature 1
Yih-Chun Hu, Adrian Perring, David B. Johnson, “Packet Leashes: A Defence against Wormhole Attacks in Wireless Ad Hoc Network, “Proc of INFOCOM 2003, San Francisco, Calif., USA, April 2003.
Non-Patent Literature 2
L. Lazos, R. Poovendran, C. Meadows, P. Syverson, L. W. Chang, “Preventing Wormhole Attacks on Wireless Ad Hoc Networks: A Graph Theoretic Approach, “Wireless Communications and Networking Conference, 2005 IEEE, 1193-1199 Vol. 2.
With respect to a harmless wormhole, however, in spite of a fact that it is desirable to use it, according to the methods of Non-Patent Literatures 1 and 2, the harmless wormhole cannot be used.
When the method of Non-Patent Literature 1 is used, it is necessary to set a proper restriction distance parameter in accordance with a radio wave arrival distance. Since the actual radio wave arrival distance, however, changes moment to moment according to elements such as transmission-electric power, receiving sensitivity, diffraction or reflection of the radio wave, existence of an obstacle such as building, mountain, or automobile, and temperature, it is actually very difficult to match the restriction distance parameter with the radio wave arrival distance. For example, when the restriction distance is longer than the actual radio wave arrival distance, by forming the wormhole extending between a position in the actual radio wave arrival distance and a position out of the restriction distance, the data of the node existing within the restriction distance can be transmitted through the wormhole.
When the method of Non-Patent Literature 2 is used, there is such a problem that even if a certain node set the common key between the node and the node existing at a relatively far position and, thereafter, a radio wave propagation environment has been changed and a communication link between both of the nodes has been cut, the wormhole established before the communication link is cut is still valid. That is, even if the communication link is cut, the data of the node existing within the restriction distance can be transmitted through the wormhole.
The present invention has been made in consideration of the problems as mentioned above and it is an object of the invention to provide a radio communication terminal and a radio communication system, in which while using a harmless wormhole, an obstacle that is caused by a malicious wormhole can be avoided.
According to the invention, there is provided a radio communication terminal having a relay route setting part for setting a relay route of a transmission packet to one of nodes in a multihop communication network in accordance with a discrimination result which is obtained by a route searching process of the multihop communication network, a transmitting part for transmitting the transmission packet through the set relay route, a receiving part for receiving a reception packet through the multihop communication network, and an application data processing part for processing application data included in the reception packet, comprising: a backup route storing part for storing the relay route as a backup route regarding the one node; and a route change setting part for having the relay route setting part obtain the backup route from the backup route storing part in accordance with a detection of an obstacle caused due to the application data by the application data processing part and change and set the obtained backup route as the relay route regarding the one node.
According to the invention, there is provided a radio communication terminal having a transfer destination setting part for setting one of a plurality of nodes in the multihop communication network as a transfer destination node of the packet and a transfer part for transferring the packet to the transfer destination node, wherein the terminal further comprises a transfer destination forced changing part for having the transfer destination setting part set a node of a transferring source of a transfer destination change command as the transfer destination node in accordance with the transfer destination change command received through the multihop communication network.
According to the invention, there is provided a radio communication system including sink nodes for mutually transmitting and receiving packets through a multihop communication network and at least one normal node, wherein the sink node comprises: a relay route setting part for setting a relay route of a transmission packet to the one normal node in accordance with a discrimination result which is obtained by a route searching process of the multihop communication network; a transmitting part for transmitting the transmission packet through the set relay route; a receiving part for receiving a reception packet through the multihop communication network; an application data processing part for processing application data included in the reception packet; a backup route storing part for storing the relay route as a backup route regarding the one normal node; a route change setting part for having the relay route setting part change and set the backup route as a relay route regarding the one normal node in accordance with a detection of an obstacle caused due to the application data by the application data processing part; and a transfer destination change command generating part for generating a transfer destination change command indicating that a transfer destination node of a transfer packet due to the one normal node should be changed in accordance with the detection and having the transmitting part transmit the transfer destination change command to the one normal node after the relay route setting part has set the relay route, and the normal node comprises: a transfer destination setting part for setting one of a plurality of nodes in the multihop communication network as a transfer destination node of the transfer packet; a transfer part for transferring the transfer packet to the transfer destination node; and a transfer destination forced changing part for having the transfer destination setting part set a node of a transmitting source of the transfer destination change command as the transfer destination node in accordance with the transfer destination change command.
According to the invention, there is provided a radio communication terminal having a relay destination setting part for setting one of a plurality of nodes in the multihop communication network as a relay destination node of the packet and a relay part for relaying the packet to the relay destination node, wherein the terminal further comprises a relay destination forced changing part for having the relay part relay a transfer destination change command to a transmission destination node in accordance with the transfer destination change command transmitted to the transmission destination node as one of the nodes which has arrived through the multihop communication network and having the relay destination setting part set a node of a transmitting source of the transfer destination change command as the relay destination node.
According to the invention, there is provided a radio communication system in which a sink node and a normal node mutually transmit and receive packets through at least one relay node in a multihop communication network, wherein the sink node comprises: a relay route setting part for setting a relay route of a transmission packet to the normal node in accordance with a discrimination result which is obtained by a route searching process of the multihop communication network; a transmitting part for transmitting the transmission packet through the set relay route; a receiving part for receiving a reception packet through the multihop communication network; an application data processing part for processing application data included in the reception packet; a backup route storing part for storing the relay route as a backup route regarding the normal node; a route change setting part for having the relay route setting part obtain the backup route from the backup route storing part in accordance with a detection of an obstacle caused due to the application data by the application data processing part and change and set the obtained backup route as the relay route regarding the normal node; and a transfer destination change command generating part for generating a transfer destination change command indicating that a transfer destination node of a transfer packet due to the normal node should be changed in accordance with the detection and having the transmitting part transmit the transfer destination change command to the normal node after the relay route setting part has set the relay route, the relay node comprises: a relay destination setting part for setting one of a plurality of nodes in the multihop communication network as a relay destination node of the relay packet; a relay part for relaying the relay packet to the relay destination node; and a relay destination forced changing part for relaying the transfer destination change command to the normal node by the relay part in accordance with the transfer destination change command to the normal node which arrived through the multihop communication network and having the relay destination setting part set a node of a transmitting source of the transfer destination change command as the relay destination node, and the normal node comprises: a transfer destination setting part for setting one of a plurality of nodes in the multihop communication network as a transfer destination node of the transfer packet; a transfer part for transferring the transfer packet to the transfer destination node; and a transfer destination forced changing part for having the transfer destination setting part set the node of the transmitting source of the transfer destination change command as the transfer destination node in accordance with the transfer destination change command.
According to the radio communication terminal and the radio communication system of the invention, while using a harmless wormhole, an obstacle that is caused by a malicious wormhole can be avoided.